In our U.S. Pat. No. 5,896,713, filed Nov. 13, 1997, owned by the same assignee as the present invention, a tubular skylight is disclosed for illuminating rooms inside buildings with natural light. As recognized therein, not only do tubular skylights save electricity and, concomitantly, are environmentally benign, but they illuminate rooms in a pleasing way using natural sunlight instead of 60 cycle electric light.
With the above in mind, the tubular skylights made by the present assignee have been commercially successful. This commercial success, however, has led to a need to provide tubular skylights that can be ever more easily and quickly installed, preferably minimizing the number of tools required to install the skylights and preferably reducing the cumbrousness of the installation procedure.
In addition to facilitating the quick and easy installation of skylights, the present invention recognizes that to ensure satisfactory skylight performance over a prolonged period, it is important to effectively seal the interior of the skylight, so that moisture and dust from inside the illuminated room and/or from the external environment does not enter the skylight and thereby reduce the light transmissive properties of the skylight. For this reason, it is important to effectively seal both the roof-mounted skylight dome to the vertical, internally-reflective tube assembly of the skylight, and to seal the room-mounted diffuser at the bottom of the tube to the tube.
As recognized by the present invention, however, many existing skylight seals are less than effective, resulting in moisture and dust entering the skylight tube and reducing its lighting capability. Also, existing seals for the bottom diffuser ordinarily require two seals, one to seal the diffuser to a bottom ring that holds the diffuser, and a second seal to seal the bottom ring to the tube assembly. As recognized by the present invention, it is desirable to minimize the number of parts that are required to seal the skylight.
Furthermore, the present invention understands that thermal stress can cause the tube to move relative to the building, and that such movement can further reduce the integrity of the skylight assembly. As recognized herein, however, it is possible to provide an expansion joint for a tubular skylight that not only absorbs thermal stress, but that also establishes an effective thermal shield.
Accordingly, the present invention addresses the above-discussed considerations.